The mean cell volume of the patient is 90 fl and the reticulocyte production index is low. Which of the following is the most possible cause of anemia in this patient?

Correct Answer: C

Rationale: The correct answer is C: Aplastic anemia. Aplastic anemia is characterized by a low reticulocyte production index due to bone marrow failure, leading to decreased red blood cell production and subsequently causing anemia. Thalassemia (choice A) is a genetic disorder resulting in abnormal hemoglobin production, not bone marrow failure. Vitamin B12 deficiency (choice B) can lead to macrocytic anemia, not a low reticulocyte production index. Sideroblastic anemia (choice D) is characterized by abnormal iron metabolism in the bone marrow, not bone marrow failure.

Correct Answer: A

Rationale: The correct answer is A because Burkitt's lymphoma is associated with translocation of c-myc gene on chromosome 8, not chromosome 18. This translocation leads to uncontrolled cell proliferation. Choice B is incorrect because Burkitt's lymphoma commonly presents with jaw or facial bone involvement in HIV patients. Choice C is incorrect as the association between Epstein Barr infection and malaria exposure in African children increases the risk of Burkitt's lymphoma. Choice D is incorrect because Burkitt's lymphoma is histologically characterized by a 'starry sky' appearance due to macrophages engulfing apoptotic tumor cells, not due to the presence of the c-myc translocation.

Correct Answer: D

Rationale: Step-by-step rationale for why the correct answer is D (Iron deficiency anemia): 1. Koilonychias is characterized by spoon-shaped nails, a classic sign of iron deficiency anemia due to changes in nail structure. 2. Iron deficiency leads to decreased production of keratin, causing nail deformities like koilonychias. 3. Hemolytic anemia (choice A) and Sickle cell disease (choice B) are not typically associated with koilonychias. 4. Thalassemia major (choice C) can cause nail changes, but koilonychias is more commonly seen in iron deficiency anemia.

Correct Answer: B

Rationale: The correct answer is B: Irradiating the blood components before transfusion. Graft versus host disease occurs when donor T-cells attack the recipient's tissues in bone marrow transplant patients. Irradiating blood components helps to deactivate T-cells in the donor blood, preventing them from attacking the recipient's tissues. Transfusion of packed cells (A) or fresh whole blood (C) does not address the issue of T-cell activation. Replacement by crystalloids (D) is not a solution for preventing graft versus host disease.

Correct Answer: C

Rationale: Rationale: A peripheral blood smear showing an increase in neutrophils, basophils, eosinophils, and platelets is indicative of Chronic Myelocytic Leukemia (CML). Neutrophils, basophils, and eosinophils are myeloid lineage cells typically elevated in CML. The presence of increased platelets is also common in CML due to the overproduction of cells in the bone marrow. Summary of other choices: A: Acute myeloid leukemia - Typically presents with a predominance of immature myeloid cells like blasts, rather than an increase in mature myeloid cells. B: Acute lymphoid leukemia - Primarily involves lymphoid lineage cells, not myeloid cells as seen in the blood smear. D: Chronic lymphocytic leukemia - Characterized by an increase in mature lymphocytes, not myeloid cells like neutrophils, basophils, and eosinophils.